Science with X-ray Free-Electron Lasers

The discovery of X-rays in 1895 allowed the determination of the atomic structure of matter, the spatial arrangement of atoms in molecules and solids, and since then the science community has strived for ever more brilliant X-ray sources. It was recognized since the 1960’s that electron accelerators and storage rings, thanks to the phenomenon of synchrotron radiation, are the most powerful X-ray sources on Earth. In recent years, a further step was taken by sources based on linear accelerators, the Free-Electron Lasers, producing X-ray pulses with peak brilliance exceeding that of synchrotron beams by up to 9 orders of magnitude, with ultra-short duration, ~ 10 fs (10 -14 s), and with a high (laser-like) degree of transverse coherence. The latest and most powerful addition to the existing X-ray Free-Electron Lasers (XFEL’s), the European XFEL, resulting from the collaboration of 12 countries including Spain, and now operating in Hamburg, will be described, including the scientific motivations and the main features of the new source, comprising a 17.5 GeV superconducting linac accelerator, almost 2 km long, and three (later to be upgraded to five) undulators.

Examples of applications of the new sources to time-resolved studies in the sub-ps range (“molecular movies”) of chemical reactions, biochemical processes such as photosynthesis, and technologically relevant solid-state processes are briefly discussed, together with possible future developments.

The Nobel Prize in Physics 2017:
Spacetime ripples and flashes of light

José Antonio Font
Universidad de Valencia

On September 14 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected the first gravitational-wave signal, GW150914. This historical discovery confirmed a century-old prediction of Einstein’s theory of general relativity - the very existence of gravitational waves - and opened an entirely new way to study the cosmos. American scientists Rainer Weiss, Barry C. Barish, and Kip S. Thorne were awarded the Nobel Prize in Physics for the accomplishment. The breakthrough detection of the tiny ripples of spacetime generated when two black holes collide has been subsequently followed by three additional detections of binary black hole signals, GW151226, GW170104, and GW170814. The latter was jointly detected by LIGO and the European interferometer Virgo, which greatly enhanced the sky localization of the event. Only three days after the last binary black hole detection, the LIGO/Virgo detectors accomplished another tremendous achievement with the first observation of gravitational waves from a binary neutron star coalescence, GW170817. This time around, the spacetime ripples produced during the inspiral and merger of the two neutron stars were accompanied by flashes of light across the entire electromagnetic spectrum, and triggered an unprecedented multi-instrument observational campaign which has just opened the era of multi-messenger astronomical observations. This talk will discuss what are gravitational waves and how they are produced. It will also explore the theoretical and experimental efforts that have finally made possible the detection of gravitational waves, winding-up Einstein’s magnificent intellectual legacy on the centenary of the formulation of his theory of general relativity.

Celebrating the Nobel Prize in Chemistry 2017
“Cryoelectron microscopy: the coming of age of a structural biology technique”

Electron microscopy has been instrumental in the development of cellular and molecular biology over the last decades thanks to its use as a descriptive technique, capable of visualizing cellular and subcellular structures. However, although it is known since the 60s that electron microscopy is in principle capable of determining the structure of biological molecules even at atomic resolution, technical limitations had made this goal almost beyond reach. After a lengthy period of steady changes, however, a series of recent instrument developments and improved computer implementations has led to a revolution in the application of electron microscopy to structural biology, the so called “resolution revolution”. The awards to Jacques Dubochet, Joaquim Frank and Richard Henderson of the Nobel Prize in Chemistry 2017 give credit to some of the scientists who have made this revolution possible.